Previously, we reported an in vitro evaluation regarding antibacterial effects against F. psychrophilum by a new Cu (I) complex, [Cu(NN1)2](ClO4). This study presents the results of an in vivo evaluation of [Cu(NN1)2](ClO4) added as a dietary supplement against F. psychrophilum in rainbow trout. The results showed that the administration of [Cu(NN1)2](ClO4) at 29 and 58 µg/g of fish for 15 days does not affect the growth of rainbow trout. On the other hand, the amount of copper present in the liver, intestine, and muscle of rainbow trout was determined. The results showed that the amount of copper in the liver, when compared between treated fish and control fish, does not change. While, in the intestine, an increase in the fish fed at 58 µg/g of fish was observed. In muscle, a slight decrease at 29 µg/g was obtained. Additionally, copper concentrations in the pond water after 15 days of feeding with the [Cu(NN1)2](ClO4) complex showed the highest levels of copper. Finally, the effect of the administration of [Cu(NN1)2](ClO4) for 15 days at 58 µg/g of fish was evaluated against F. psychrophilum, where a 75% survival was obtained during 20 days of challenge.

Biofilm formation in pathogenic bacteria is an important factor of resistance to antimicrobial treatments, allowing them to survive for a long time in their hosts. In the search for new antibiofilm agents, in this work we report the activity of a copper (I) complex, [Cu(NN1)2]ClO4, synthesized with Cu (I) and NN1, an imine ligand 6-((quinolin-2-ylmethylene)amino)-2H-chromen-2-one, a derivate of natural compound coumarin. The antibacterial and antibiofilm capacity was evaluated in Vibrio harveyi BB170 used as model bacteria. Antibacterial activity was measured in vitro by minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and half-maximal inhibitory concentration (IC50) determination. Antibiofilm capacity of copper (I) complex was analyzed by different concentrations of IC50 values. The results showed that the sub-IC50 concentration, 12.6 µg/mL of the copper (I) complex, was able to reduce biofilm formation by more than 75%, and bacterial viability was reduced by 50%. Inverted and confocal laser scanning microscopy showed that the [Cu(NN1)2]ClO4 complex affected the biofilm structure. Therefore, the copper (I) complex is effective as an antibiofilm compound in V. harveyi BB170.